They would be truly Epic Crashes if GT5 had debris , semi-realistic collision damanges, wheels coming off, unusable cars immediately following the crash. As it is, there is no fun in driving in reverse, or ramming into AI for that matter. currently, it's like kicking a washing machine in slippers. (note: I don't do that, just laymen speak)
It's fun watching your car fly 40+ feet into the air and the other cars spin out and pile up. Why would I want my car to be completely wrecked after first crash? Unless of course you like restarting races.